In company with the continuous development of interventional materials and devices as well as interventional cardiology, minimally invasive treatment using an interventional occluder via catheter has become an important method for treating ventricular septal defect (VSD), atrial septal defect (ASD), patent ductus arteriosus (PDA), patent foramen ovale (PFO) and other congenital heart diseases. In addition, it is a widely accepted treatment method for carrying out endovascular closure using an intervention means.
For example, Chinese Patent No. 97194488.1 discloses a heart occluder. As shown in FIGS. 1 and 2, this heart occluder comprises bolt head 1, metal mesh 2, flow-occluding membrane 3, and closure head 4. As shown in FIG. 5, a steel sleeve 6 used for fixing metal mesh 2 is provided at one end of bolt head 1. Steel sleeve 6 is fitted and fixed by means of welding in blind hole 7 at one end of bolt head 1. As a result, the entire metal mesh 2 is connected to bolt head 1, forming one end of the wires 201 of the metal mesh 2 and one welding head 203. An internally threaded bore 8 is formed at the other end of bolt head 1. Said internally threaded bore 8 is used to connect and fix the device that transports the occluder.
In addition, for example, Chinese Patent No. 200780010436.7 discloses an occluder. As shown in FIGS. 3 and 4, this occluder comprises bolt head 101, metal mesh 102, and flow-occluding membrane 103. The structure of the bolt head is basically the same as that shown in FIG. 5. This structure has no closure head compared with FIG. 1, and the braided mesh has an integral closed structure.
Although the aforementioned two occluders can occlude cardiac septal defects or blood vessels, they both have obvious structural defects. The structure shown in FIG. 1 has a permanent closure head at the distal end (the distal end is defined as the end that is away from the operator during the operation). As a result, the amount of the metal left in the human body is increased. If the closure head and the metal mesh are made of different metal materials, local galvanic corrosion will occur, and the electric field thereof will damage the physiological environment of the surround tissues and increase the risk of having broken metal wires at that location. The large amount of metal ions released also has an adverse effect on the surrounding tissues over the long term. Meanwhile, since the closure head sticks out permanently, it not only causes long-term damage to the tissues inside the heart but also is not conducive to epithelialization by the endothelial tissue. The structure shown in FIG. 3 has no closure head so that the aforementioned risk can be avoided. However, when this occluder is placed back into the sheath, serious accumulation of metal wires will occur at the distal end. As a result, the resistance incurred when placing the occluder back into the sheath during the surgery becomes excessively large (if a larger sheath is used, extra damage will be caused by the sheath to the vascular wall). The risk of the surgery is increased. Meanwhile, the application range of the device is reduced.